Maximum meter



YUNITED STATES PATENT FFTCE.

MAXIMUM METER.

SPECIFICATION forming part of Letters Patent No. 601,256, dated March29A, 1898. Application iled July 29, 1897. Serial No. 646,333. (Nomodel.)

To all whom z lt may concern.-

Be it known that I, ADRIAN H. Hov'r, a

` v citizen of the United States, residing atPenacook, in the county ofMerrimac andState of New Hampshire, have invented .certain new anduseful Improvements in Maximum Meters; and I do hereby declare thefollowing to be a full, clear, and exact description of the invention,such as will enable others skilled inthe art to which it appertains tomake and use the same.

My invention relates to maximum meters which register thermally.

It is highly essential in the construction of a thermal instrument ofthis character that all heat should be practically confined to the bulborheating area of the thermal tube-z'. e. that there should be noperceptible heat in any other part of the instrument. After muchexperimenting in this -field I have found that the metal carrying thecurrent around the bulb should be as thin as possible, for if thickmetal is used I find the area to be heated is considerably reduced andthecapacity of the metal limited by numerous air-spaces which occurbetween the metal and the bulb, as thick metal cannot be uniformlyfitted to the bulb Without danger' of breaking it, and to obviate thisdimculty I use two strips of thin metal wholly surrounding the bulb andconnected in parallel, one strip passing over the posterior and theother over the anterior of the heating area, thus permitting the use ofmetal of a given thickness one-half the length with one-quarter theheating capacity and allowing such instruments to be made of much higherrange. I also nd that in the manufacture ofl ammeters or instruments oflow resistance, where it is necessary to use a shunt, the connectionsinthe circuit should be absolutely uniform at all times and that anordinary hinge'is ineffective. Inv the drawings I show a hinge of novelform which is expressly adapted for this purpose and quite accurate inoperation. By means of this construction I am enabled to shunt theinstrument at its rear terminal, thereby permitting instruments oflarger carrying capacity to operate with the same degree of accuracy oflow-reading instruments of any form.

The object of my invention is to simplify and cheapen the construction,to improve the electrical conductivity of the hinge, and to utilize themaximum heating area of the thermal bulb in instruments of thischaracter; and my invention consists in the novel constructions, asfully set forth in the following specification and claims, and clearlyillustrated in the drawings accompanying and forming a part of the same,of which- Figure 1 is a front elevation of a maximum meter tol which myimprovements are applied. Fig. 2 is an edge view of same. Fig. 3 is myimproved hinge connection in section. Fig. 4 is a sectional plan showingthe heating area or bulb and my improved electrical conductorssurrounding the same.

Similar reference-letters denote like parts lin all the. views.

A is a wooden base carrying a graduated scale B and a suitable thermaltube C, the heating area of which is the bulb c, which is preferablycylindrical, as shown.

This thermal tube is made in form of a U, having a bulb at each end andcontains a suitable liquid, as indicated, the bulbs containing air orgas. my improved heating resistances D D, formed vof thin metal, eachstrip being long enough to more than cover one-half the area of the bulbc, the projecting portions d d being secured by screws at opposite sidesof said bulb to the movable member of one of my improvedelectrically-connected hinges or to an extension e thereof, as shown andto be hereinafter explained. The tube C has near its bulb c anoverflow-tube C', and as the current passing through the resistances D Dincreases the gas in the bulb c expands, causing the liquid in the bulbc to overiiow into the tube C', which may be read by the scale B.

The stationary member ofthe hinge, as indicated in sectional detail,Fig. 5, consists of ablock F, secured to abase or plate G, formed ofrubber or other insulating material, said block having an opening f'extending through its side and through a cylindrical extension f', towhich the perforated end of the movable member E is fitted and securedthereon by a suitable collar f2, which is shrunk or otherwise rigidlysecured to said cylindrical extension f. Such a hinge can be made toform quite a sure electrical connection between its stationary landmovable members.

The bulb c is surrounded by IOOA This instrument may be easily shunted,as seen in Fig. 2, by means of a bar f3, rigidly fastened to the block Fand extending rearward and horizontally through a partition or supportand to which bar a plate or bar f1 may be secured and adapted to carry awire Y.

Having described my improvements, what I Claim isl. In a thermalregistering maximum meter, two strips of thin metal covering oppositesides of the heating area of the thermal tube and electrically connectedin parallel, and similarly connected to the stationary and movable partsof the instrument.

2. In a thermal registering maximum meter, an electrieally-eonnectedhinge connecting the stationary and movable parts of the instrument, andthin metal plates closely fitting and surrounding the cylindricalportion of the heating area of the thermal tube and electricallyconnected in parallel to the movable member of said hinge.

3. An electrically-eonnected hinge comprising a stationary body having areduced lateral extension, said body being perforated longitudinally andthrough said lateral extension, a movable body bored to fit said lateralsleeve or extension, a collar shrunk upon or otherwise tightly fittingsaid extension and against the movable body, and one or more screwsthreaded to the stationary body and its collar and adapted to theperforation of the former, all substantially for the purpose Set forth.

In testimony whereof I affix my signature 3 5 in presence of twowitnesses.

ADRIAN II. HOYT. lllitnesses:

J. B. THURsToN, HENRY E. BURNHAM.

